A conventional drill chuck typically comprises a chuck body, a plurality of jaws, a nut, a nut jacket, a rolling member, a front sleeve, a rear sleeve, and a locking means. The jaws, usually three, are respectively inserted into three angled bores uniformly distributed around the chuck body of the drill chuck device. The nut is fitted in a nut groove of the chuck body. The threads of the nut and the threads of the jaws together form a thread driving mechanism to drive the jaws back and forth. The nut jacket is fixedly connected to the nut. The front sleeve is mounted around nut jacket and connected to the nut via keys. The rear sleeve is mounted around the rear end portion of the body.
The present invention relates to a kind of drill chuck device, particularly to a self-locking drill chuck device. During assembling and using a drill with a drill chuck device according to the present invention, a threaded rod of a driving shaft of a driving device of the drill is connected with a threaded hole defined in the rear end portion of the chuck body. When the driving shaft is driven to rotate, the chuck body, which is driven by the driving shaft, drives the three jaws to rotate together with a tool fastened therein, such as a drill head. When assembling the tool, the front sleeve and the rear sleeve fixedly connected with the chuck body are rotated relatively, thereby the front sleeve drives the nut to rotate. Meanwhile, the jaws threadingly engaged with the nut move forward or backward along the angled bores in the chuck body, so the handle of the tool, i.e., the toolholder of the drill head, is fastened by the jaws or released therefrom. The tools for the drill chuck device usually comprises screw driver, nut drivers, burrs, mounted grinding stone and drill head etc.
In order to increase the chucking effects and reliability of the drill chuck, various additional locking means may be selectively adopted. For example, several types of locking means for the drill chucks are respectively disclosed in PCT/CN02/00375 and PCT/CN02/0399. Although the drill chuck as described in PCT/CN02/00375 has a simple and compact structure, this type of drill chuck is mainly applied for DC type impact drill, if it is used for AC type impact drill, the locking reliability will be insufficient due to the high speed and the huge impact force. PCT/CN02/0399 disclosed a drill chuck suitable for various impact drills with good performances, however the structure of this type of drill chuck is complicated, it costs more than necessary when it is used for lower powered AC or DC impact drills.
Therefore, the conventional drill chucks have some drawbacks such as complex structure, low locking reliability due to vibration and impact and inconvenient assembling and disassembling.